Estradiol and phorbol ester cause phosphorylation of serine 118 in the human estrogen receptor.

Joel PB, Traish AM, Lannigan DA
Mol Endocrinol. 1995 9 (8): 1041-52

PMID: 7476978 · DOI:10.1210/mend.9.8.7476978

Serine 118 is definitively identified as a major site of phosphorylation in the human estrogen receptor expressed in COS-1 cells treated with estradiol or phorbol ester. At least 30% of the estrogen receptor appears to be phosphorylated on serine 118 after treatment with estradiol or phorbol ester. Human estrogen receptor was expressed in COS-1 cells and labeled in vivo with [32P]orthophosphate in the presence of estradiol or phorbol ester. Immunopurified receptor was digested with cyanogen bromide. The most heavily labeled peptide (7 kilodaltons) was identified as amino acids 110-174 by microsequencing. Manual Edman degradation released a major portion of the 32P-label in the peptide at serine 118. A mutant with serine 118 replaced by alanine (S118A) had 80% less 32P-label in the 7 kilodalton peptide. Estrogen receptor labeled in vivo with [32P]-orthophosphate in the presence of estradiol or phorbol ester migrates electrophoretically as a doublet. The major difference between the bands is phosphorylation of serine 118 in the upshifted band. The mutant S118A does not show an upshifted band. Labeling of the estrogen receptor with [35S]methionine indicates that > or = 30% of the receptor is upshifted and suggests that > or = 30% of the receptor is phosphorylated on serine 118.

MeSH Terms (21)

Animals Base Sequence Cell Compartmentation Cell Nucleus Cells, Cultured Cercopithecus aethiops Cyanogen Bromide Enzyme Activation Estradiol Gene Expression Regulation HeLa Cells Humans Molecular Sequence Data Oligodeoxyribonucleotides Peptide Mapping Phosphoserine Protein Kinase C Receptors, Estrogen Recombinant Proteins RNA, Messenger Tetradecanoylphorbol Acetate

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